Patent GB-834994-A (GB)
Title: Improvements in or relating to identification apparatus for identifying a calling subscriber's station in a telecommunication system
IPC: H04M15/08
Filed: 1958-10-07
Abstract: 834,994. Party line systems. TELEFONAKTIENBOLAGET L.M. ERICSSON. Oct. 7, 1958 [Oct. 14, 1957], No. 31991/58. Class 40 (4). In a party line system in which subscribers are provided with voice-frequency senders and receivers to enable connections to be set up between them, one termination is provided with a voice-frequency receiver and registration equipment for receiving voice-frequency identification signals transmitted from the calling subscriber prior to the setting up of the call. A subscriber, by sending a special signal, may obtain access to the main exchange network in which case the identity is used to connect up an appropriate meter. Initiation of call.-Relay r67, in the subscriber's equipment AR1, AR2 operates to the calling subscriber's loop and slave relay r66 follows to bring up r41, in the line-selecting equipment LR whereupon chain relay r471 corresponding to a free line connects up the equipment AR1, AR2 to a free line. In the subscriber's equipment AR1, r51 comes up in the hold circuit of r471 and r52 follows to busy the equipment. Relay r66 brings up r68 which reverses the feed polarity to the subscriber's instrument, so disabling the microphone. Relay r52 releases r41 and r68 connects a calling tone Sua to line via transformer D53. Amplifiers SF4 at all substations and SF3 at the terminal GLR are arranged to provide an output over their terminals I if this signal is received, provided the signal is a pure tone. At all substations this signal operates r42 and r43 follows to prevent other substations seizing the line. At the terminal GLR the tone operates r35 which is followed by r34 which operates chain relay r311 associated with the line, to connect up the identification circuit IR1, IR2, IR3, wherein r1011 operates followed by r108 (momentarily), r109, r1010. Relay r109 causes dial tone Suk to be sent to line. The tone now on the line being impure relay r35 at the terminal and relays r42 at the substations release, and in the former r33 comes up to release r34. Identification of calling subscriber.-In the substation connecting equipment LR, release of r42 operates r44 and r611 follows to interrupt the calling signal Sua and at the same time complete a charging circuit for condenser C61 in a resonant circuit including a tapped inductance D614 whereby a tone indicative of the tens digit of the calling subscriber is sent to line. Relay 611 then operates r612 and r613 follows whereupon r611, r612 release to connect up a different tapping on the inductance D614 and cause the emission of the units digit frequency. Relay r63 then operates to connect the subscriber's instrument to line. At all substations r43 completes its slow release during which time it has prevented the calling subscriber identification tones from reaching the respective subscriber's equipments. In the identification equipment r1010 brings up r97 to connect up the tens digit registering relays r81 . . . r85. The identification tone is received from outlet II of the amplifier SF3 and passes to a filter F10 arranged to produce a signal on two out of five outlets for each incoming tone. Assuming the digit 1 is received the output signals operate two relays r101, r102 out of the five relays r101 ... r105. Relay r913 tests that a valid code has been received and so operates in this case to transfer the received code to register relays r81 ... r85. Relay r913 also operates r912 which releases r101, r102, whereupon r913 releases, r911 and r98 operate and r97 release. Relay r98 connects up to units registering relays r91 . . . r95. The units digit (say 2) next operates r101, r103 and r913 again operates to transfer this digit to r91 ... r95. Relay r912 releases, followed by r101, r103, r913, r911 and r99, r98 operate. At the substations release of r43 operates r471 for all idle substations which connects these substations to line. Relays r51, r52 operate, followed by r610 which disconnects the subscriber's instruments. Dial tone Suk received over outlet II of SF4 is amplified at SF6 in both calling and non-calling (idle) substation equipments so that relays r62, r65, r61 all come up therein. Call to other substations on line.-The calling subscriber on receipt of dial tone, operates his key set to send tens and units digits. Receipt of the tens digit at the identifier IK1, IR2, IR3 causes r910 to come up cutting off the dial tone Suk. In the substations the filters FTE are normally tuned to accept frequencies indicative of the subscriber's tens digit and if the received frequency is appropriate r55 operates followed by r63. On cessation of dial tone r62 releases to bring up r64 followed by r54 which resets the filter FTE to accept the appropriate units digit frequency. If the tens digit is not appropriate r63 fails to operate so that when r64 operates on cessation of dial tone, r46 comes up and releases r471 and r51 so disconnecting the subscriber's equipment AR1, AR2. When the units frequency is transmitted the receiving equipment in the identifier operates as before and r106 and r109 commences a long release period. In the stillconnected substations, if the units digit is inappropriate r55 stays down and r46 operates to initiate disconnection as previously described. If, however, the units digit is correct r62 and r55 operate and r65 releases to initiate the slow release of r61. Relay r55 brings up r69 which releases r610 which connects up a first ringing current source RG and a first ringing tone source Su2. The latter consists of more than two frequencies so that more than two relays of r101-r105 operate in which case r914 operates to bring up r32 in GLR which releases the identification equipment IR1, IR2, IR3. In the wanted subscriber's equipment AR1, AR2 relay r61 eventually releases to substitute the interrupted ringing current source RGi and ringing tone Su3. When the called subscriber answers, r69 releases differentially due to loop current and feed relay r67 operates, followed by r66. At the calling subscriber's station r62 operates to ringing tone a release r68 so changing the polarity to the subscriber's instrument to enable his microphone. When one subscriber hangs up feed-relay r67 releases, followed by r66, r58 coming up for a short period to send a disconnection tone Sun (identical with Sua). This operates r42 in the subscriber's instruments and r35 in the terminal equipment GLR. In the latter this releases the whole of the equipment. In the former r42 operates r45 whereupon r44, r45 and r471 release to disconnect the equipment AR1, AR2 from the line. In the equipment of the subscriber who hangs up last r66, r67 and r55 remain up to busy the equipment until the subscriber eventually hangs up. Called subscriber busy.-In this event no connection between his equipment and line will have been effected (because r52 is up). Thus no ringing tone is reverted and when r109 in the identifier completes its slow-release period disconnection tone Sun is sent to line. Relays r42, r35 release as before the latter releasing the terminal equipment GLR and IR1, IR2, IR3. Relay r42 releases r51 which connects busy tone Su1 to the calling subscriber. Defective signals.-In the event of a signal comprising one only, or more than two frequencies relay r914 in the identifier operates to bring up r107 which emits disconnection tone Sun and the connection is released. Call via main exchange.-After identification r99 is up as previously described. The caller now sends digit 0 which brings up r104, r105, followed by r96. All non-calling subscribers are now disconnected as the " O " frequency is not accepted by the filters FTE. Relay r96 brings up first the select magnet h21 associated with the line and secondly a chain relay r21 associated with a free exchange trunk. The latter brings up a corresponding hold magnet v21 to complete the connection to the exchange trunk and also operates rr21 which transfers the stored tens identitites to one of relays RT21 ... RT20 and the units identities to one of select magnets Hr21 ... Hr20 of a cross-bar switch whose cross-points are connected to corresponding subscriber's meters such as T12. Magnet v21 operates operating magnet Vr21 so that the exchange metering wire r is now connected to the appropriate meter. Magnet Vr21 operates r32 to free the terminal equipment GLR. In the subscriber's equipment AR after O is dialled r54, r61, r64, r65 operate as before and r613 follows. On receipt of dial tone from the exchange, r62 operates to release r65. The subscriber then sends the necessary digits, cessation of exchange dial tone after the first digit releasing r62, r613 whereafter the call proceeds in the usual manner. Disconnection is effected as previously described by a disconnection tone emitted either by the calling subscriber or by the exchange.